I can help, I have a 20g tank and tried to do it on the cheap. Here is my set-up:
1 HOB filter (get 1 size up from what you need, my tank is a 20g but I wish I had a 30g filter to help w water movement).
1 heater (I have two of the 15 g heaters to keep things even)
2 nano-koralia powerheads (i...